Two printers have upgraded their newspaper folders by replacing traditional gears and clutches with 'shaftless' servo technology from Siemens Automation and Drives.
When printing newspapers is your core business, missing deadlines is simply not an option. So when two of the UK's busiest printing houses required their newspaper folders to be overhauled, the latest technology from Siemens was deployed to replace existing mechanical drive systems with 'shaftless' systems.
At Yorkshire Post Newspapers Ltd in Leeds, an ageing folder with 16-year-old mechanical gearboxes, clutches, linkages and couplings was becoming a source of constant frustration to the site's engineering team due to repeated downtime.
"The folder was a continuous headache to us," confirms Geoff Taylor, engineering manager at YPN. "If we had a failure of the gearbox/clutch arrangement then the press would be down for 48 hours while repairs were carried out. This sort of downtime is not acceptable when there are newspapers that have to be printed."
A newspaper folder is the 'weak link' in a printing press line. A press can only go as fast as the folder will allow, hence a bottleneck is created. Folder reliability has a direct effect on printing press productivity and performance.
To remedy the situation YPN enlisted the services of Preston-based Printing Press Services, a specialist in the remanufacturing, installation and commissioning of printing machinery. Together with Siemens Automation and Drives, the preferred equipment supplier, the two companies set about designing a 'shaftless' servo system to drive the folder.
"We wanted the ability to adjust the drives to suit production requirements," says Mr Taylor. "The shaftless option was cost-effective, trouble-free and provided the capability to 'tune' the drives to the press. Without doubt, it was the right solution for us."
The Siemens approach split the mechanical system into individual drives driven by shaftless servo systems based on Siemens 1PH7 air-cooled ultra-compact AC asynchronous motors. Siemens Masterdrives were deployed on a common DC bus, while all synchronisation commands were sent across a Siemens Simolink high-speed fibre-optic ring bus. Processing for the set points was performed by one of the Masterdrives, thereby negating the need for an external PLC.
"It was a very successful project," declares Mr Taylor, "but then again, it had to be. We do not stop printing, so if there is no folder, there is no press, no Yorkshire Post, no Financial Times, no Metro, etcetera. We operate a very busy site."
Fortunately for YPN, the majority of the work could be engineered off-site, with most of the overhaul and commissioning taking place over just one weekend.
"There were difficult design criteria," says Mr Taylor. "The mechanical 'envelope' was very tight. But I cannot fault PPS or Siemens – since commissioning we have not had any downtime whatsoever. This project has increased our reliability, speed and performance, as well as saved us a considerable sum in lost production".
Across the Pennines, an almost identical problem was being experienced at Bolton-based Newsquest Printing Ltd.
"One of our folders with mechanical drives was getting a bit long in the tooth," explains print manager Paul Barker. "Gears were failing with regularity, typically around every three months. The cost of replacement parts is OK, but we cannot afford the costs of downtime."
The situation drove NPL to modify the folder and introduce the latest shaftless technology, again by employing the expertise of Printing Press Services and Siemens Automation and Drives. The aim was to engineer a complete turnkey system including panel build and harmonic mitigation to ensure a clean power supply for the system.
"We wanted Siemens as we have their PLCs on our press," says Mr Barker. "Siemens drives are excellent and their motors are smaller than equivalent models available on the market."
He goes on to list four main advantages of installing and commissioning a shaftless solution: "Firstly it has engineered-out the inherent design issues of the folder; secondly, it has eliminated the effects of mechanical drives, such as backlash; importantly, it has allowed us to gain control over speeds; and, lastly, we have also got a 2 per cent gain difference to play with."
Similar to the project in Yorkshire, NPL could ill afford any downtime for installation. However, the skills of the PPS and Siemens engineers allowed the controls, inverter, power supply and motor systems to be built and tested off the press.
"This meant that installation and commissioning could be stage-managed in bite-size chunks over a series of weekends," says Mr Barker. "It was an important factor for us because this folder handles around 750,000 copies a week."